Alarm detector with increased operating range

ABSTRACT

In an ultrasonic alarm detector of the doppler detection type including a transmitter transducer and a receiver transducer, the improvement comprising a second transmitter transducer disposed remote from the detector and driven from the master oscillator at the detector. The second transmitter is preferably disposed at the limiting range of the alarm detector and is directed in the same direction as the transmitter transducer at the alarm detector thereby extending the operating range of the detector to up to twice the range attainable without the second transmitter transducer.

.se we SR XR *3 was '46? w 5 uuuflll BI [11] 3,786,467 Cotter Jan. 15,1974 ALARM DETECTOR WITH INCREASED 3,093,809 6/1963 Watlington 340 15OPERATING RANGE 75 Inventor: William L. Cotter Bev rl M PrimaryExaminer-David Tmfton 1 e y ass Attorney-David M. Driscoll [73]Assignee: Alarmtronics Engineering, Inc., v

Ne t M 22 F1 d M w on ass [57] ABSTRACT 1 an 1972 In an ultrasonic alarmdetector of the doppler detec- PP ,868 tion type including a transmittertransducer and a receiver transducer, the improvement comprising a sec-[521 LS Cl. 340/258 A 340/16 R 340/258 B ond transmitter transducerdisposed remote from the [51] Int. Cl b 13/16 detector and driven fromthe master oscillator at the [58] Field A 258 B detector. The secondtransmitter is preferably dis- 340/13 1 6 posed at the limiting range ofthe alarm detector and .is directed in the same direction as thetransmitter 56] References Cited transducer at the alarm detectorthereby extending the operating range of the detector to up to twice theUNITED STATES PATENTS range attainable without the second transmittertrans- 2,7s2,405 2/1957 Weisz r al. 340/258 A ducen 2,655,645 10/1953Bagno 340/258 A X 2,922,999 1/1960 Carlin 340/15 11 Claims, 3 DrawingFigures \I\ /2 Al A2 I DETECTION 1 1 SECTION R I I! /0 PATENIHJJAN 1 53m DETECTION TI SECTION ALARM DETECTOR Ll 2mh 24 u 26 KHZ 22 RETURNTRANSMITTER TRANSDUCER ALARM DETECTOR WITH INCREASED OPERATING RANGERELATED APPLICATIONS The subject matter of patent application Ser. No.205,599, entitled Ultrasonic Alarm Circuit, filed Dec. 7, 1971 is herebyincorporated by reference herein. This copending'application, which isdiscussed in more detail hereinafter, discloses an ultrasonic dopplerdetection circuit including a transmitter. transducer and a receivertransducer. The incorporation of the copending application is in no wayto be construed as limiting the appended claims of the present inventionto the specific detector circuit disclosed and claimed therein.

FIELD OF THE INVENTION The present invention pertains in general to analarm system preferably disposed within a secured area for detecting thepresence of an intruder in the secured area. More particularly, thepresent invention relates to a preferably ultrasonic doppler detectionsystem including a remote transmitter transducer driven by an oscillatorcomprising in part the detection circuitry for the system and directedso as to extend the operating range of the system.

BACKGROUND OF THE INVENTION In one embodiment of the alarm circuitdisclosed in the copending application Ser. No. 205,599, the maximumrange of detection in a secured area is about 30 feet. It would beadvantageous to extend this detection range up to another 30 feet butknown techniques for extending the range involve the expenditure ofsufficient additional costs so that it is almost as easy to just providetwo detectors for these larger areas to be secured. One known techniqueis to provide a second transmitter/receiver transducer arrangement andassociated circuitry. This technique is generally too costly.

The use of a single remote receiver transducer has also been tried butdid not extend the detection range sufficiently to warrant its use.However, quite unexpectedly the placement of a transmitter transducer atabout the limiting range of the basic detector directed preferably inthe samerdirection as the transmitter transducer as sociated with thebasic detector extended the detection range to twice the normal 30 feetrange. Also, this extension of the range by the employment of the remotetransmitter transducer added little cost to the basic detector.

OBJECTS OF THE INVENTION Accordingly, it is a primary object of thepresent invention to provide an alarm detection system including aremote transmitter means for extending the detection range of the basicdetector.

Another object of the present invention is to provide an improved alarmdetection system in accordance with the primary object and that maybefabricated at only a small additional cost over the cost of the basicdetector arrangement which includes both transmitter and receivertransducers.

A further object of the present invention is to provide an alarmdetection system in accordance with the preceding objects wherein theaddition of the remote transmitter transducer can be readily made toexisting detectors with little added cost and with the need for only afew tie wires to the remote transmitter means.

SUMMARY OF THE INVENTION To accomplish the foregoing and other objectsof the present invention the alarm detection system comprises a basicdetector generally including an oscillator or the like for generating anultrasonic signal such as 26 K HZ signal, means for transmitting theultrasonic signal to establish an ultrasonic wave pattern in the area tobe secured, means for receiving the reflected ultrasonic signal, andmeans responsive to the transmitting means and the receiving means forregistering a doppler signal of a frequency corresponding to thevelocity of motion in the area. The latter means includes means forgenerating an alarm condition when an intruder motion is detected in thesecured area.

The improvement in accordance with the present invention resides in theuse of a second transmitter means preferably including a transmittertransducer disposed remotely from the transmitting means of the basicdetector but excited from the oscillator at the basic detector. Thisremote transmitting means is disposed approximately at the limitingrange of the basic detector and is directed toward the additional areato be secured so as to extend. the detection range of the system tocover this additional area. In one embodiment the range of the basicdetector is about 30 feet and the remote transmitting means is disposedabout 30 feet from the basic detector and is directed in substantiallythe same direction as the transmitting means of the basic detector tothereby extend the detection range to approximately 60 feet from thebasic detector. In another e'mbodiment wherein the secured area includesan L- BRIEF DESCRIPTION OF THE DRAWINGS Numerous other objects, featuresand advantages of the present invention will now become apparent upon areading of the following detailed description taken in conjunction withthe appended drawings in which:

FIG. 1 is a schematic block diagram of one embodiment of .the alarmdetection system of the present invention; v

FIG. 2 is a partial circuit, partial block diagram of theremote-transmitting means of the present invention shown in a block inFIG. 1; and I I FIG. 3 is a schematic block diagram of anotherarrangement for the alarm detection system of the present invention foruse in an L-shaped area.

DETAILED DESCRIPTION Referring now to the drawings and in particular tothe diagram of FIG. 1, there is shown an alarm detection systemincluding a detector l0'of the ultrasonic doppler detection type whichmay be of conventional design. The detector includes a detection section1.2, a transmitter transducer Tl and a receiver transducer R. Thedetector 10, when operating independently, excites transmittertransducer Tl to establish an ultrasonic wave pattern in the area Al,depicted as a dotted circle. The receiver transducer R receives thereflected ultrasonic signal and the detection section 12 registers adoppler signal of a frequency corresponding to the velocity of motion inarea Al. Detection section 12 also includes means for generating analarm when intruder motion is detected.

One ultrasonic alarm detector is disclosed in copending application Ser.No. 205,599, referred to hereinbefore. That detector is depicted in FIG.1 of that application as including a transmitter transducer excited froman oscillator, a receiver transducer, a phase detector, time andfrequency filter means and output alarm circuitry. There are also manyother detector arrangements that may be employed in the presentinvention.

FIG. 1 also shows a remote transmitter means T2 disposed in thedisclosed embodiment, at the edge of area AI diametrically oppositedetector 10. A tie line 14 couples from detector to transmitter means T2and this remote means is directed in substantially the same direction asis the transmitter transducer T1 of detector 10. With the remotetransmitter means positioned as indicated in FIG. 1 the detection rangeof the detector 10 is extended into an additional area A2 which is aboutthe same size as area Al. In one embodiment the distance from detector10 to remote transmitter means T2 is 30 feet which is the approximatemaximum range for the detector when operated independently, and theextended range (diameter of area A2) attained by use of remote means T2is 30 feet. The remote transmitter means T2 may be placed at a distanceless than the limiting range of the basic detector, but shouldpreferably not be placed too far outside the area Al or there will be ablind spot in the detection system.

Referring now to FIG. 2, there is shown one embodiment for the remotetransmitter means T2 of FIG. 1 including the tie line 14 coupled fromdetector 10, a buffer circuit 16 and a remote transmitter transducer 18which may, per se, be of conventional design. The tie line 14 includesthree separate lines, namely; the DC power line 20, the return line 22and the 26K I-Iz signal line 24. The buffer circuit includes a tunedtank circuit including capacitor C1 and inductor L1 which is resonantabout 26 KHz, and transistor Q1. The 26 KHz signal from an oscillator ofthe detector 10 couples to the base electrode of transistor 01. Theemitter electrode of the transistor connects to the ground return lineand the collector'electrode couples to one side of the tank circuit. Theother side of the tank circuit connects to line 20, thereby providing abiasing path for transistor 01. The transmitter transducer 18 receives asignal input from the collector electrode of the transistor and an inputfrom line 22. Transistor O1 is a buffer amplifier and representsessentially no load to the oscillator at the main detector. The threeconductor tie line 14 is preferably a shielded cable with the shieldbeing grounded at both ends of the cable to provide low signal loss.

FIG. 3 shows a schematic block diagram of another arrangement for thealarm detection system of the present invention. In this arrangement thesecured area is L-shaped including a first area A1 having the detector10 disposed at one end thereof and extending to approximately thelimiting range (illustratively, 30 feet) of the detector, and a secondarea A2 extending at right angles to the longitudinal direction of areaA1. Normally, without the use of the remote transmitting means T2 theintruder motion in area A2 cannot be detected. It has been found that bydisposing the transmitsay 15 feet, intruder motion in area A2 can bedetected by disposing transmitting means T2, as shown, and exciting itfrom the main'oscillator of the detector. The

, transmitter means T2 may be the same configuration as depicted in FIG.2.

One advantage to the system of the present invention is that theincreased detection range can be obtained quite easily andinexpensively. Only a relatively simple circuit such as the one depictedin FIG. 2 is added to the basic detector along with a tie line.

Having described a limited number of embodiments of the presentinvention, numerous other embodiments and modifications thereof shouldnow become apparent to one skilled in the art, and all such embodimentsare contemplated as falling within the spirit and scope of the presentinvention. For example, only two configurations of areas to be securedhave been considered herein. However, it is intended that otherconfigurations shall fall within the scope of the present invention. Forinstance, if the secured area is cross-shaped two or more remotetransmitting means may be employed, each directed toward a differentarea. Also, with respect to FIG. 1, if the secured area is notrectangular in shape but instead has an angular bend therein the remotetransmitting means is not directed in exactly the same direction as thetransmitting means of the basic detector but is at an angle thereto. Itis important in each different secured area that the remote transmittingmeans be directed toward the additional area to be secured. Furthermore,it is expected that many different types of basic detectors can beemployed in the present invention. Also, the remote transmitting meansmay have a different configuration than that shown specifically in FIG.2.

What is claimed is:

1. In an alarm detection system for use in a secured area comprising adetector having means for generating an ultrasonic signal, first meansfor transmitting the ultrasonic signal to establish an ultrasonic wavepattern in the area, means for receiving the reflected ultrasonicsignal, said first means for transmitting and said means for receivingbeing disposed at a first site, and means for registering adopplersignal of a frequency corresponding to the velocity of motion in thearea including means for registering an alarm condition, the improvementcomprising; 4

second means for transmitting an ultrasonic signal coupled from andresponsive to said means for generating an ultrasonic signal, saidsecond means for transmitting being disposed at a second site remotefrom the first transmitting means and directed so as to extend thedetection range of said system,

said means for registering a doppler signal capable of being responsiveto said second means for transmitting, I

said first means for transmitting including a transmitter transducer,said means for receiving including a receiver transducer, and saidsecond means for transmitting including a transmitter transducer,

and means for coupling the ultrasonic signal to said second means fortransmitting and including a multi-wire tie line.

2. The system of claim 1 wherein said second means for transmitting isdisposed within the detection range of said detector when operatedindependently without 5. The system of claim 4 wherein said resonantcir-' cuit includes a tank circuit and said amplifier means includes atransistor coupled to said tank circuit.

6. The system of claim 5 wherein said tie line includes a power line,return line and signal line.

7. An Alarm detection system for use in an area to be securedcomprising;

an oscillator for providing an ultrasonic signal, first transmittingmeans including a first transmitter transducer for directing theultrasonic signal into the secured area to establish an ultrasonic wavepattern in a first part of the secured area, means for receiving thereflected ultrasonic signal, said first transmitting means and saidmeans for re ceiving being disposed at a first site, means responsive tosaid first transmitting means and said means for receiving forregistering a doppler signal of a frequency corresponding to thevelocity of motion in the area including meansfor registering an alarmcondition, second transmitting means including a second transmittertransducer disposed at a second site remote from said first site anddirected toward and having an operating range covering a second part ofthe secured area,

and means coupling said ultrasonic signal to said second transmittertransducer.

8. In an alarm detection system for use in a secured area, said systemcomprising firstmeans for trahsmit ting an ultrasonic signal toestablish an ultrasonic wave pattern in the area, means for receivingthe reflected ultrasonic signal, and means for registering a dopplersignal of a frequency corresponding to the velocity of motion in thearea the improvement comprising;

second means for transmitting an ultrasonic signal,

said first means for transmitting being disposed at a first site andhaving an operating range covering a first portion of the secured area,

said means for receiving being disposed at the first site, said secondmeans for transmitting being disposed at a second site remote from saidfirst means for transmitting and directed toward and having an op-' saidmeans for registering being responsive to reflected signals from bothsaid first and second means for transmitting.

9. The system of claim 8. wherein said second means for transmitting isdisposed approximately at the limiting range of said first means fortransmitting.

10. The system of claim 8 comprising conductive means for coupling theultrasonic signal to said second transmitting means.

11. The system of claim 8 wherein said first means for transmitting isdirected in a first direction and said second means for transmitting isdirected in a second direction approximately orthogonal to said firstdirection.

1. In an alarm detection system for use in a secured area comprising adetector having means for generating an ultrasonic signal, first meansfor transmitting the ultrasonic signal to establish an ultrasonic wavepattern in the area, means for receiving the reflected ultrasonicsignal, said first means for transmitting and said means for receivingbeing disposed at a first site, and means for registering a dopplersignal of a frequency corresponding to the velocity of motion in thearea including means for registering an alarm condition, the improvementcomprising; second means for transmitting an ultrasonic signal coupledfrom and responsive to said means for generating an ultrasonic signal,said second means for transmitting being disposed at a second siteremote from the first transmitting means and directed so as to extendthe detection range of said system, said means for registering a dopplersignal capable of being responsive to said second means fortransmitting, said first means for transmitting including a transmittertransducer, said means for receiving including a receiver transducer,and said second means for transmitting including a transmittertransducer, and means for coupling the ultrasonic signal to said secondmeans for transmitting and including a multi-wire tie line.
 2. Thesystem of claim 1 wherein said second means for transmitting is disposedwithin the detection range of said detector when operated independentlywithout said second means for transmitting connected.
 3. The system ofclaim 2 wherein said second means for transmitting is disposed at aboutthe maximum range of said detector to thereby extend the composite rangeto twice the original range.
 4. The system of claim 1 wherein saidbuffer circuit includes a resonant circuit and amplifier means bothcoupled to said second transmitter transducer.
 5. The system of claim 4wherein said resonant circuit includes a tank circuit and said amplifiermeans includes a transistor coupled to said tank circuit.
 6. The systemof claim 5 wherein said tie line includes a power line, return line andsignal line.
 7. An Alarm detection system for use in an area to besecured comprising; an oscillator for providing an ultrasonic signal,first transmitting means including a first transmitter transducer fordirecting the ultrasonic signal into the secured area to establish anultrasonic wave pattern in a first part of the secured area, means forreceiving the reflected ultrasonic signal, said first transmitting meansand said means for receiving being disposed at a first site, meansresponsive to said first transmitting means and said means for receivingfor registering a doppler signal of a frequency corresponding to thevelocity of motion in the area including means for registering an alarmcondition, second transmitting means including a secoNd transmittertransducer disposed at a second site remote from said first site anddirected toward and having an operating range covering a second part ofthe secured area, and means coupling said ultrasonic signal to saidsecond transmitter transducer.
 8. In an alarm detection system for usein a secured area, said system comprising first means for transmittingan ultrasonic signal to establish an ultrasonic wave pattern in thearea, means for receiving the reflected ultrasonic signal, and means forregistering a doppler signal of a frequency corresponding to thevelocity of motion in the area the improvement comprising; second meansfor transmitting an ultrasonic signal, said first means for transmittingbeing disposed at a first site and having an operating range covering afirst portion of the secured area, said means for receiving beingdisposed at the first site, said second means for transmitting beingdisposed at a second site remote from said first means for transmittingand directed toward and having an operating range covering a secondportion of the secured area, said means for registering being responsiveto reflected signals from both said first and second means fortransmitting.
 9. The system of claim 8 wherein said second means fortransmitting is disposed approximately at the limiting range of saidfirst means for transmitting.
 10. The system of claim 8 comprisingconductive means for coupling the ultrasonic signal to said secondtransmitting means.
 11. The system of claim 8 wherein said first meansfor transmitting is directed in a first direction and said second meansfor transmitting is directed in a second direction approximatelyorthogonal to said first direction.